Leaf-miner: The
larva feeds within the needle from the tip to base and exits close
to the base (British
leafminers).

The
mine begins at an oval egg on the flat side of the tip of a needle.
Working from here the larva mines the needle for about one quarter
of its length. Apart from the larval chamber, the entire mine is
filled with frass. The full grown larva leaves the mine by an opening
made at the end of te mine, then forms a cocoon between a few needles
that have been spun together. Only the pupa enables discrimination
from O. piniarella (Bladmineerders van Europa).